/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2008 University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.util;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * @author pugh
 */
public abstract class MergeMap<K, V> {

	public static class MinMap<K, V extends Comparable<? super V>> extends MergeMap<K, V> {
		@Override
		protected V mergeValues(V oldValue, V newValue) {

			if (oldValue.compareTo(newValue) > 0)
				return newValue;
			return oldValue;
		}
	}

	public static class MaxMap<K, V extends Comparable<? super V>> extends MergeMap<K, V> {

		@Override
		protected V mergeValues(V oldValue, V newValue) {

			if (oldValue.compareTo(newValue) < 0)
				return newValue;
			return oldValue;
		}
	}

	final Map<K, V> map;

	protected abstract V mergeValues(V oldValue, V newValue);

	public MergeMap() {
		map = new HashMap<K, V>();
	}

	public MergeMap(Map<K, V> map) {
		this.map = map;
	}

	public V put(K k, V v) {
		V currentValue = map.get(k);
		if (currentValue == null) {
			map.put(k, v);
			return v;
		}
		V result = mergeValues(currentValue, v);
		if (currentValue != result)
			map.put(k, v);

		return result;
	}

	public V get(K k) {
		return map.get(k);
	}

	public boolean containsKey(K k) {
		return map.containsKey(k);
	}
	public Set<Map.Entry<K, V>> entrySet() {
		return map.entrySet();
	}

	public static void main(String args[]) {

		MergeMap<String, Integer> m = new MaxMap<String, Integer>();

		m.put("a", 1);
		m.put("a", 2);
		m.put("b", 2);
		m.put("b", 1);
		System.out.println(m.entrySet());

	}

}
